1. Field of the Invention
The present invention relates to a needle adaptor into which a needle, containing a taken-in sample, is inserted to inject the sample and to an automatic sampler using the needle adaptor.
2. Description of the Related Art
An automatic sampler for injecting a sample into an analytical flow path of a liquid chromatograph includes a flow path switching valve having a plurality of ports and switching connection between the ports as well as a needle for taking in the sample. The flow path switching valve has the ports connected to the analytical flow path of the liquid chromatograph via pipes and the port forming an injection port into which the needle is inserted and connected. By connecting the ports and injecting the sample from the needle into the injection port, the flow path switching valve introduces the sample into the analytical flow path of the liquid chromatograph (see Japanese Unexamined Patent Publication No. 2003-215118). An example of a flow path configuration of such an automatic sampler is shown in FIG. 6.
The automatic sampler in FIG. 6 includes a plurality of pipe connecting ports 50a, a port 50b for an injection port, and a flow path switching valve 50 for switching connection between the ports. A needle adaptor 52 is mounted to the port 50b for the injection port and the needle adaptor 52 forms the injection port for injecting the sample with a needle 6. The automatic sampler also includes the needle 6 and a syringe pump 10 connected, via pipes, to the pipe connecting ports 50a of the flow path switching valve 50. The needle 6 is connected to the syringe pump 10 by the flow path switching valve 50 to thereby suction and discharge a solvent from its tip end.
The needle 6 can be moved to a position of the needle adaptor 52, a position of a sample vial 2 on a rack 4 disposed in an apparatus, and a position of a cleaning port 16 of a cleaning mechanism 13. The needle 6 inserts its tip end into the sample vial 2 to suction the sample, keeps the sample in a sample loop 12, and then moves to the position of the needle adaptor 52 to inject the sample into the injection port.
An upstream analytical flow path 18 and a downstream analytical flow path 22 forming an analytical flow path of the liquid chromatograph are connected to the two pipe connecting ports 50a of the flow path switching valve 50. The upstream analytical flow path 18 includes a solvent delivery pump 20 for delivering a mobile phase and the downstream analytical flow path 22 includes an analytical column 24 and a detector (not shown). By inserting and connecting the needle 6 into the needle adaptor 52 and switching the state of the flow path switching valve 50 so that the upstream analytical flow path 18, the needle 6, and the downstream analytical flow path 22 are connected, the sample taken in from the tip end of the needle 6 can be introduced into the analytical column 24 by the mobile phase.
An example of a structure of the flow path switching valve 50 will be described with reference to sectional views in FIGS. 7A and 7B.
Each of the pipe connecting ports 27 includes a connecting hole 27a formed in an upper face of a stator 36 and a flow path 27b and the port for the injection port includes a connecting hole 55 formed in the upper face of the stator 36 and a flow path 55a. In a valve body 26, a circular columnar rotor 32 is housed with one of its circular faces oriented toward the upper face of the stator 36. One end of a shaft 30 is connected to the other circular face of the rotor 32, and the other end of the shaft 30 extends outside from a lower face side of the valve body 26 and is driven by a driving mechanism (not shown) disposed outside.
The one circular face of the rotor 32 and a lower face of the stator 36 are disposed to come in direct contact with each other. The rotor 32 is provided with a port connecting flow path 38 for connecting the adjacent ports in the upper face of the stator 36. When the shaft 30 rotates, the rotor 32 rotates as well to switch the flow paths. In order to increase liquid tightness between the rotor 32 and the stator 36, the rotor 32 is pushed against the stator 36 by a spring 34.
A bottom portion of each of the connecting holes 27 in the upper face of the stator 36 communicates with the lower face of the stator 36 through the flow path 27b and a bottom portion of the port hole 55 for the injection port communicates with the lower face of the stator 36 through the flow path 55a. A pipe fixing member 40 mounted to a tip end portion of the pipe can be fixed into the connecting hole 27 by engaging threads by screwing and the pipe can be connected to the flow path 27b by fixing the pipe fixing member 40. The needle adaptor 52 can be fixed into the port hole 55 for the injection port by engaging threads by screwing. The needle adaptor 52 has a hole 52a into which the needle 6 is to be inserted, and a needle seal 52b is disposed at a bottom portion of the hole 52a. 
In the above example, in order to reduce a capacity of the flow path, through which the sample injected into the injection port from the needle passes, to suppress a phenomenon that a detection peak obtained by the liquid chromatograph is broad, the needle adaptor 52 is directly mounted into the port hole 55 for the injection port of the flow path switching valve 50. Because the pipe connecting member 40 and the needle adaptor 52 have different structures, it is necessary to provide the port 50b for the injection port separately from the pipe connecting port 50a. Therefore, the flow path switching valve 50 having the port 50b for the injection port cannot be formed by a general flow path switching valve, which increases the number of parts forming the automatic sampler.